Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2000-06-30
2002-12-17
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C522S091000, C528S028000, C528S049000, C528S069000, C528S075000
Reexamination Certificate
active
06495651
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a process for preparing an urethane compound for medical instruments. More particularly, the present invention relates to a process for easily preparing an urethane compound (macromonomer) showing high safety, which is very useful for a material of medical instruments represented by optical materials such as a contact lens material and an intraocular lens material. Furthermore, the present invention relates to a process for preparing an urethane compound while molecular weight of the compound is controlled.
At present, various urethane compounds such as urethane foam, urethane rubber, adhesives and polyurethane synthetic fiber are industrially used.
In the absence of a catalyst or in the presence of a compound such as an organic metal compound or a tertiary amine, hydroxyl group is reacted with isocyanate group to form urethane bond. Particularly, from the viewpoint of high catalytic activity, the organic metal compounds are generally used. Among them, an organic tin compound is well known.
However, it is considered that the organic tin compound which is generally known as a compound showing high toxicity must not be used as a catalyst for preparation of urethane materials when the urethane materials are applied for medical instruments which are used in living organism or by contacting with living organism. The organic tin compound is recognized as a distraction substance for endocrine (environmental hormone) which is recently topical substance. Accordingly, some catalysts other than organic tin compounds are earnestly necessitated.
From the viewpoint of mechanical strength and excellent oxygen permeability, urethane bond-containing siloxane compounds (macromonomers) have been examined for the use as medical instruments, in particular, optical materials such as a contact lens material and an intraocular lens material (Japanese Unexamined Patent Publication No. 22487/1979, Japanese Unexamined Patent Publication No. 121826/1994, U.S. Pat. No. 5,451,617 and the like). However, because the siloxane compounds disclosed in these references are prepared by using the organic tin compounds almost, these siloxane compounds are not suitable as medical materials on the basis of the above reasons. Even if purification of the siloxane compound is carried out, the organic tin compounds remain within the siloxane compound.
Usually, the above urethane bond-containing siloxane compounds (macromonomers) have been prepared by finally introducing a polymerizing group in a polyfunctional polysiloxane which is a main chain through urethane bond (Japanese Unexamined Patent Publication No. 179217/1986, Japanese Unexamined Patent Publication No. 35014/1991 and the like). However, when this method is employed, it is inevitable that the polymerizing group is inestimably and repeatedly introduced in the polyfunctional polysiloxane which is a main chain through urethane bond. As a result, molecular weight of the obtained siloxane compound becomes higher than planned molecular weight. Accordingly, there is a problem that clear understanding for structure of the obtained compound is difficult.
Because the above siloxane compound becomes a high viscous solution according to its molecular weight or kind of reaction components, effective purification methods for the siloxane compound are not developed. So, it is very difficult to remove impurities such as the above catalyst and by-products, and crude siloxane compound is used. Accordingly, the use of the siloxane compounds has been feared from the viewpoint of safety, including the above problems.
An object of the present invention is to provide a process for easily preparing an urethane compound, in particular, while molecular weight of the compound is controlled, in the absence of a catalyst or in the presence of a catalyst showing lower toxicity instead of the conventional organic tin compounds.
This and other objects of the present invention will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a process for preparing an urethane compound for medical instruments, characterized by reacting a hydroxyl compound (A) with an isocyanate compound (B) in the absence of a catalyst or in the presence of a reaction catalyst other than an organic tin compound to give an urethane compound (I).
According to the process of the present invention, an urethane compound showing high safety, which is very useful for a material of medical instruments represented by optical materials can be easily prepared, in particular, while molecular weight of the compound is controlled.
DETAILED DESCRIPTION
In the process for preparing an urethane compound for medical instruments, as mentioned above, the hydroxyl compound (A) is reacted with the isocyanate compound (B) to give an urethane compound (I) in the absence of the catalyst or in the presence of the reaction catalyst other than the organic tin compound in order to more accelerate this reaction.
In consideration of the use of the urethane compound as a material for medical instruments, preferable examples of the above reaction catalyst are an organic iron compound and an amine compound because of excellent safety.
Examples of the above organic iron compound are, for instance, iron(III) acetylacetonate and the like.
Examples of the above amine compound are, for instance, a cyclic tertiary amine such as triethylenediamine, an aliphatic tertiary amine such as trimethylamine or triethylamine, an aromatic tertiary amine such as dimethylaniline or triphenylamine, and the like.
Because molecular weight of the urethane compound can be more sufficiently controlled, the organic iron compound is particularly preferable.
In order to sufficiently exhibit acceleration effect for the progress of reaction, it is desired that the amount of the reaction catalyst is, on the basis of weight, at least 1 ppm, preferably at least 30 ppm of the total amount of the hydroxyl compound (A) and the isocyanate compound (B). In order to prevent removal of the reaction catalyst from being finally difficult after the finish of reaction, it is desired that the amount of the reaction catalyst is, on the basis of weight, at most 10000 ppm, preferably at most 3000 ppm of the total amount of the hydroxyl compound (A) and the isocyanate compound (B). The amount of the reaction catalyst can be suitably adjusted within the above range according to kind of the hydroxyl compound (A) and the isocyanate compound (B) in urethane reactions (i) and (ii) as mentioned below.
In the present invention, it is desired that the above compound (I) is prepared by, for instance, the following two-step urethane reactions (i) and (ii).
At first, in the urethane reaction (i), at least one member of dihydroxyl compounds (A-2) is used as the hydroxyl compound (A) and at least one member of diisocyanate compounds (B-2) is used as the isocyanate compound (B), so the dihydroxyl compound (A-2) is reacted with the diisocyanate compound (B-2). As a result, at least two urethane bonds are formed between hydroxyl group in the dihydroxyl compound (A-2) and isocyanate group in the diisocyanate compound (B-2).
When 1 mole of the dihydroxyl compound (A-2) is reacted with 2 moles of the diisocyanate compound (B-2), two urethane bonds are formed and a compound having isocyanate groups in its both ends respectively through two urethane bonds is synthesized. On the other hand, when 2 moles of the dihydroxyl compound (A-2) is reacted with 1 mole of the diisocyanate compound (B-2), two urethane bonds are formed and a compound having hydroxyl groups in its both ends respectively through two urethane bonds is synthesized.
In the urethane reaction (i), the dihydroxyl compound (A-2) is not limited to one member and the diisocyanate compound (B-2) is also not limited to one member. So, at least two members of each compound can be used with suitable combination. Accordingly, in a compound synthesized in the urethane reaction (i), units derived from at least two members of t
Ichinohe Shoji
Ito Eri
Tanikawa Sadayasu
Watanabe Tsuyoshi
Yamazaki Toshio
Armstrong Westerman & Hattori, LLP
Gorr Rachel
Menicon Co. Ltd.
LandOfFree
Process for preparing urethane compound for medical instruments does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for preparing urethane compound for medical instruments, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing urethane compound for medical instruments will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2922820